1. Field of the Invention
The present invention relates to a light emitting diode (LED) package, and more particularly, to a side view LED package having an elongated cavity.
2. Discussion of the Background
LED packages are formed by mounting an LED chip to various types of packages depending on use. Particularly, a side view LED package is mainly used as a display backlight source, and is disposed at a side of a light guide plate to provide light in parallel with the light guide plate.
FIGS. 1 and 2 are plan and perspective views of a conventional side view LED package, respectively.
Referring to FIGS. 1 and 2, the LED package comprises a pair of lead terminals, i.e., first and second lead terminals 11 and 13. The first and second lead terminals 11 and 13 are supported by a package body 15. The package body 15 may be formed by insert-molding with the lead terminals inserted therein.
For convenience of illustration, the package body 15 may be divided into upper and lower package bodies 15a and 15b based on a position of the first and second lead terminals 11 and 13.
The upper package body 15a has an elongated cavity 16 which allows the first and second lead terminals 11 and 13 to be exposed. The first and second lead terminals 11 and 13 are positioned on the bottom surface of the cavity 16, i.e., on the lower package body 15b, and are spaced apart from each other within the cavity 16. Further, the respective first and second lead terminals 11 and 13 protrude outwardly from the package body 15 so as to be electrically connected to an external power source. The outwardly protruding portions of lead terminals 11 and 13 may have a variety of shapes or be bent into various shapes. FIGS. 1 and 2 illustrate the lead terminals 11 and 13, which are bent from a lower surface of the package body 15 to a side surface thereof.
An LED chip 17 is mounted on the first lead terminal 11 in the cavity 16 and electrically connected thereto and is electrically connected to the second lead terminal 13 through a bonding wire. The cavity 16 may be filled with an encapsulant made of a transparent resin, and phosphors may be incorporated in the transparent resin.
The conventional side view LED package comprises the elongated cavity 16, and its inner sidewalls, particularly its inner sidewalls 15w positioned in a major axis direction, are slantingly formed, thereby increasing a viewing angle along the major axis direction. Such a side view LED package is suitable for a backlight source for a display, which is disposed at a side of a light guide plate, and white light can be emitted from the side view LED package by properly selecting the LED chip 17 and phosphors.
However, in the conventional side view LED package, it is limited to adjust an orientation angle of light emitted from the LED chip 17, and it is difficult to control the properties of light, including an orientation angle and the like, only by the limited shape of the cavity and encapsulant filled therein. Therefore, it is required to make continuous attempts to control the properties of light, including an orientation angle and the like, in the side view LED package. Further, the conventional side view LED package is inefficient because a large number of LED packages are required to supply light parallel with a light guide plate.
In addition to the side view LED package, another type of LED package, e.g., a top view LED package, also has a limit in adjusting an orientation angle of light emitted from an LED chip. Therefore, it is required to adjust an orientation angle having a predetermined direction and angle size for obtaining a desired light efficiency.
Particularly, when a plurality of LED packages are used as a light source of a backlight unit, the light emitted from each LED package is necessarily emitted to have a wide orientation angle in order to obtain a uniform backlight. However, a conventional side view LED package does not provide a uniform light in a backlight unit since it is difficult to control an orientation angle.
Accordingly, a technique for mounting a patterned lens on an upper surface of a package body of an LED package has been proposed to adjust an orientation angle and the like. However, such a technique is easily applied to a top view LED package having a circular cavity, but it is difficult to apply the technique to an LED package having a small thickness and an elongated and narrow cavity, such as a side view LED package. In addition, when a lens is mounted on an upper surface of a body of an LED package, the entire size of an optical system is increased and light loss results from the increase of the distance of a path through which light emits to the outside via an encapsulant and the lens.